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August 24, 2021

The Truth About Mixes And Foraging

by Dr. Cayla Iske, PhD

True or False: Mixes will stimulate my pet's instinctual foraging behaviors.

FALSE: One claim that some manufacturers have begun to make regarding mixes is that the variety of food pieces will stimulate natural foraging behaviors in your pet.  Newer “foraging blends” lean heavily on this claim.   

Foraging is indeed an extremely important and instinctual behavior for small pets, but it must be done correctly to provide any benefit.  Rather than encouraging natural foraging behaviors, mix-based diets often trigger a separate, detrimental instinctual behavior: selective feeding. 

What is selective feeding?

In nature, small animals spend hours each day foraging for sustenance.  As prey species, these animals are wired to consume the most calorically dense foods first; this behavior is referred to as “concentrate selecting” and is directly tied to the survival instinct.  In the process, prey species are instinctively wired to consume the most calorically dense foods first. 

This behavior is directly tied to survival in the wild.  With predators potentially lurking around every corner, it’s essential for small prey animals to consume as many calories as possible, as quickly as possible.

Wait…my pet isn’t wild.  Why do I have to worry?

Great question! Selective feeding is an instinctual behavior that remains intact when animals make the transition from “wild” to “child.”  When offered low-quality nutrition options with a variety of pieces, the natural concentrate-selecting behavior of small mammals will often drive them to eat the least nutritionally appropriate components of the diet first.  These components include pieces primarily made up of low fiber, high starch, high sugar ingredients. 

Examples of ingredients small pets are likely to eat first, given the opportunity, include:

  • Dried fruits
  • Dehydrated veggies
  • Flower petals  
  • Starchy extruded pieces
  • Nuts & seeds

Selective feeding in domesticated small mammals has been observed and documented for decades and occurs when an animal preferentially consumes only certain pieces of the mix, leaving the rest until their bowl is refilled with more preferred pieces.1-4

Okay, that makes sense.  I just won’t refill the bowl until everything is gone. 

While you may have the best of intentions, most pet parents find it incredibly difficult to stay disciplined with those little bunny or piggy eyes looking at you, begging for more food.

  • Research surveys have documented that 70% of rabbit owners will refill their pet’s food bowl when there is still uneaten food left in it.1
  • This directly leads to selective feeding, imbalanced nutrition, and likely eventual negative health impacts.

True or False: Mixes will help keep my pet active and spend more time feeding.

FALSE: It seems logical to assume that a food containing a variety of tastes and textures would encourage pets to spend more time feeding.  In reality, published research looking at this specific topic proves the opposite to be true. 

  • Published research comparing mixes to uniform pellets has shown that mixes actually lead to greater inactivity in pets, especially if the foods aren’t paired with loose hay.7
  • Additionally, rabbits fed a uniform food alongside timothy hay spent more time feeding compared to those fed a muesli diet paired with timothy hay.7
  • It is clear to see that the claims of stimulated activity and feeding time are simply not true when animals are fed mixes, especially without free choice hay.

True or False: Foraging blends are better for my pet than other variety mixes.

FALSE: A recent trend in small animal food involves some mixes being branded as “foraging blends,” with specific claims that these foods are designed to encourage a pet’s natural foraging activities.  The ingredient profiles of these products vary, with some focusing on a more natural appeal by including ingredients such as dried fruit, veggies, and beans, flowers, and seeds.   

Another ingredient that’s popular in foraging blends is loose hay.  While hay is centrally important to the diet and health of small herbivores, the amount of hay included in foraging blends is often trivial and presented in small, choppy pieces.

The inclusion of hay to give these mixes a more “natural” appearance offers little to no impact nutritionally or behaviorally.  In reality, research has shown animals may eventually become uninterested in the hay and select for other pieces in the mix.

Despite product claims, foraging mixes will still result in selective feeding which in turn leads to an imbalanced diet.

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References

  1. Harcourt-Brown, F.M. 1996. Calcium deficiency, diet and dental disease in pet rabbits. Veterinary Record 139.23: 567-571.
  2. Lebas, F., P. Coudert, H. De Rochambeau, and R.G. Thébault. 1997. The Rabbit - Husbandry, Health and Production (2d edition) FAO publ., Rome, pg. 223.
  3. Mullan, S.M., and D.C.J. Main. 2006. Survey of the husbandry, health and welfare of 102 pet rabbits. Veterinary Record 159.4: 103-109.
  4. Meredith, A.L., J.L. Prebble, and D.J. Shaw. 2015. Impact of diet on incisor growth and attrition and the development of dental disease in pet rabbits. Journal of Small Animal Practice 56.6: 377-382.
  5. Prebble, J.L., and A.L. Meredith. 2014. Food and water intake and selective feeding in rabbits on four feeding regimes. Journal of Animal Physiology and Animal Nutrition 98.5: 991-1000.
  6. Jekl, V., and S. Redrobe. 2013. Rabbit dental disease and calcium metabolism–the science behind divided opinions. Journal of Small Animal Practice 54.9: 481-490.
  7. Prebble, J.L., F.M. Langford, D.J. Shaw, and A.L. Meredith. 2015. The effect of four different feeding regimes on rabbit behaviour. Applied Animal Behaviour Science 169: 86-92.
  8. Miller, G.R. 1968. Evidence for selective feeding on fertilized plots by red grouse, hares, and rabbits. The Journal of Wildlife Management: 849-853.
  9. Somers, N., B. D’Haese, B. Bossuyt, L. Lens, and M. Hoffmann. 2008. Food quality affects diet preference of rabbits: experimental evidence. Belgian Journal of Zoology 138.2: 170-176.
  10. Gidenne, T., F. Lebas, and L. Fortun-Lamothe. 2010. Feeding behaviour of rabbits. In: Nutrition of the Rabbit, Eds: de Blas, C. and Wiseman, J. CAB International. Pgs: 254-274.
  11. Mykytowycz, R., 1958. Continuous observations of the activity of the wild rabbit, Oryctolagus cuniculus (L.), during 24-hour periods. C.S.I.R.O. Wildl. Res.
  12. Myers, K., and W.E. Poole. 1961. A study of the biology of the wild rabbit, Oryctolagus cuniculus (L.), in confined populations II. The effects of season and population increase on behaviour. C.S.I.R.O. Wildl. Res. 6, 1–41.
  13. Gibb, J.A. 1993. Sociality, time and space in a sparse population of rabbits (Oryctolagus cuniculus). Journal of Zoology 229.4: 581-607.
  14. Franz, R., M. Kreuzer, J. Hummel, J.M. Hatt and M. Clauss. 2011. Intake, selection, digesta retention, digestion and gut fill of two coprophageous species, rabbits (Oryctolagus cuniculus) and guinea pigs (Cavia porcellus), on a hay‐only diet. Journal of Animal Physiology and Animal Nutrition 95.5: 564-570.
  15. National Research Council (NRC). 1977. Nutrient Requirements of Rabbits: Second Revised Edition. Washington, DC: The National Academies Press.
  16. European Pet Food Industry Federation (FEDIAF), 2013: Nutritional Guidelines for Feeding Pet Rabbits. FEDIAF, Brussels (Belgium).
  17. Lowe, J.A. 2010. Pet Rabbit Feeding and Nutrition. In C. de Blas and J. Wiseman (eds.) Nutrition of the Rabbit 2nd ed.). CAB International. Pp. 294-313.
  18. Gidenne, T. 2003. Fibres in rabbit feeding for digestive troubles prevention: respective role of low-digested and digestible fibre. Livestock Production Science 81.2-3: 105-117.
  19. Rees Davies, R. and J.A.E. Rees Davies. 2003. Rabbit gastrointestinal physiology. Veterinary Clinics: Exotic Animal Practice 6.1: 139-153.
  20. DeCubellis, J, and J. Graham. 2013. Gastrointestinal disease in guinea pigs and rabbits. Veterinary Clinics: Exotic Animal Practice 16.2.: 421-435.
  21. Melillo, A. 2007. Rabbit clinical pathology. Journal of Exotic Pet Medicine 16.3: 135-145.
  22. Clauss, M., B. Burger, A. Liesegang, F. Del Chicca, M. Kaufmann-Bart, B. Riond, M. Hassig, and J.M. Hatt. 2012. Influence of diet on calcium metabolism, tissue calcification and urinary sludge in rabbits (Oryctolagus cuniculus). Journal of Animal Physiology and Animal Nutrition 96.5: 798-807.
  23. Tschudin, A., M. Clauss, D. Codron, A. Liesegang, and J.M. Hatt. 2011. Water intake in domestic rabbits (Oryctolagus cuniculus) from open dishes and nipple drinkers under different water and feeding regimes. Journal of Animal Physiology and Animal Nutrition 95.4: 499-511.